The present invention relates to a flow control device, and in particular to a flow control device which has an internal post in a passage channel which, in cooperation with an annular flexible member defines a control gap between the annular flexible member and the outer peripheral surface of the internal post to provide flow control under a range of pressures.
Devices for controlling the rate of flow of a fluid, primarily liquids, at varying line pressures, are utilized in a variety of applications, such as clothes washers and dishwashers, showers, faucets and plumbing valves, drinking fountains, ice makers, water softeners, automotive heating systems, fuel systems, water cooled equipment and heat exchangers, gas valves, pneumatic machine tools, respiratory controls, and water sprinklers.
One device capable of providing effective control for this wide variety of installations is a rubber flow control washer, which can be routinely engineered to maintain a constant flow rate despite variations in line pressure. For example, various rubber flow control washers are available for maintaining an essentially constant flow in a range of from less than 1 gpm to flows in excess of 100 gpm under pressure variations ranging from 15 psi to 150 psi.
Regardless of the specific application, generally a flow control washer is designed by specifying a rubber or rubber-like material having a requisite modulus of elasticity, thickness, diameter, contour and flow aperture to give the desired quantity of flow over a range of pressures likely to be encountered in the specific application for which the flow control has been designed.
It should also be noted that there is a class of valves which incorporate an apertured rubber or rubber-like member received between two relatively rigid members that can be advanced toward and retracted away from each other to squeeze and release the rubber part to change the diameter of the opening through it. For example, U.S. Pat. Nos. 1,657,663; 3,072,151; 3,095,175; and 3,833,019 each show constructions of this general type in which an attempt is made to control flow by changing the diameter of the orifice through a resilient valve element.
It should be noted, however, that devices of this type merely adjust the flow rate for a given line pressure, but fail to provide for pressure variations that may occur, so that if pressure increases with a device of this type, the flow rate will also increase, and conversely, should the line pressure decrease the flow rate will decrease.
In the particular applications shown in the above-noted patents, flow control under varying line pressure may not be of sufficient importance to warrant a control responsive to pressure variations. For example, U.S. Pat. No. 1,657,663 discloses a device adapted to control the flow of a lime emulsion or solution used for flotation in minerals separating apparatus, U.S. Pat. Nos. 3,072,151 and 3,095,175 are directed to devices for use in butane or propane lighters, and U.S. Pat. No. 3,833,019 covers a quick-connect fitting for a trickle type irrigation system.
Conventional flow control valves typically have a relatively limited range of pressures over which the control will regulate flow. Depending on the flow tolerance chosen, this range is typically about 6:1, highest to lowest pressure. A conventional flow control typically achieves flow control by constricting upon itself, that is, there is typically nothing inside the central hole so flow control depends on the flexible portion geometry constricting radially inward in such a way as to provide constant flow. It has proven difficult to devise the appropriate geometry to achieve the desired flow control over a wide range of pressures.
It would be desirable to have a flow control device which regulates flow over a wider range flow curve. Furthermore, it would be desirable to have a flow control design which allows for modifications or variations in the controlled flow rate by altering the size or shape of one or more components of the flow control. The ability to modify more than one variable in the design process allows more flexibility in the design and increased operating range.